Review of Octocorallia (Cnidaria: Anthozoa) from Hawai‘i and Adjacent Seamounts. Part 3: Genera Thouarella, Plumarella, Callogorgia, Fanellia, and Parastenella1

Ten species of Hawaiian primnoids are described and/or discussed, completing the review of the 28 primnoids known from the Hawaiian Islands. This family constitutes 29% of the Hawaiian octocoral fauna. Callogorgia americana is synonymized with C. gilberti, resulting in a disjunct distribution in the Pacific and Northwest Atlantic. Two new species are described (Plumarella circumoperculum Cairns and Parastenella bayeri Cairns), and two (Callogorgia gilberti and C. robusta) are reported for the first time since their original descriptions over a century ago. Keys are provided for the Hawaiian primnoid genera and all species of the genus Parastenella; comparative tables are provided for the Hawaiian Callogorgia and Fanellia. A distinctive nematocyst pad is described for the genus Parastenella. Highly modified polyps caused by copepod parasites are described for two species: Callogorgia gilberti and Thouarella hilgendorfi.